This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 20 |
| 5 | 1655 |
| 6 | 65305 |
| 7 | 1794730 |
| 8 | 40179930 |
| 9 | 793030245 |
| 10 | 14423331635 |
| 11 | 248261291960 |
| 12 | 4113063835540 |
| 13 | 66327037011235 |
| 14 | 1049050826515965 |
| 15 | 16360528085273190 |
| 16 | 252545239130514350 |
| 17 | 3869090307434050625 |
| 18 | 58948119057416280295 |
| 19 | 894447719738683138420 |